THE FIRST OF FOUR GENERAL SECTIONS CONTAINS ARTICLES THAT DISCUSS METHODS OF BEHAVIOR GENETIC RESEARCH IN PSYCHOPATHOLOGY. RESEARCH UTILIZING PATIENTS, PATIENTS' FAMILIES, AND PATIENTS' CHILDHOOD RECORDS IS CRITICALLY REVIEWED, AND THE LONGITUDINAL STUDY OF HIGH-RISK SAMPLES IS RECOMMENDED AS THE SUPERIOR STUDY METHOD. ANOTHER PAPER IN THIS SECTION PRESENTS A NUMBER OF EXPERIMENTAL DESIGNS, RELYING MAINLY UPON ADOPTIONS, TO UNRAVEL HEREDITARY AND ENVIRONMENTAL FACTORS. THE SECOND SECTION IS COMPOSED OF PAPERS DEALING WITH A DANISH HIGH-RISK PROJECT BEGUN IN 1962 THAT EXAMINED 207 CHILDREN WHOSE MOTHERS WERE JUDGED SEVERELY AND CHRONICALLY SCHIZOPHRENIC AND 104 CONTROL CHILDREN CAREFULLY MATCHED WITH THE 207 FOR AGE, SEX, FATHER'S OCCUPATIONAL STATUS, RURAL-URBAN RESIDENCE, YEARS OF FORMAL EDUCATION, AND INSTITUTIONAL VERSUS FAMILY REARING CONDITIONS. THE STUDY INCLUDED BIOMEDICAL, PSYCHOPHYSIOLOGICAL, SOCIAL, COGNITIVE, AND PERSONALITY MEASURES. THE STUDY WAS BASED UPON THE EMPIRICAL FINDING THAT A RELATIVELY HIGH PERCENTAGE OF CHILDREN OF SCHIZOPHRENICS BECOME SCHIZOPHRENIC. PAPERS PRESENTED IN RELATION TO THIS RESEARCH DISCUSS PREMORBID CHARACTERISTICS RELATED TO BREAKDOWN IN CHILDREN WITH SCHIZOPHRENIC MOTHERS, POSSIBLE PREDISPOSITIONAL PERINATAL FACTORS INVOLVED IN SUCH BREAKDOWNS, THE RECOVERY LIMB OF THE SKIN CONDUCTANCE RESPONSE IN 'HIGH-RISK' RESEARCH, AND ELECTRODERMAL RECOVERY AND PSYCHOPATHOLOGY. A THIRD SECTION IS COMPOSED OF A GROUP OF STUDIES WHICH HAVE CONTRIBUTED TO THE ELUCIDATION OF GENETIC FACTORS IN PSYCHOPATHOLOGY. THE ADOPTION METHODOLOGY IS USED IN THESE STUDIES IN EXAMINING FACTORS CONTRIBUTING TO SHIZOPHRENIA. SUBSEQUENT STUDIES OF PSYCHOPATHY, CRIMINALITY, AND ALCOHOLISM ARE ALSO TREATED. THE PAPERS IN THE FINAL SECTION EXAMINE A NUMBER OF ENVIRONMENTAL VARIABLES POSSIBLY RELATED TO SCHIZOPHRENIA, FROM DEVELOPMENT IN THE UTERUS TO SOCIAL CLASS. REFERENCES AND A SUBJECT INDEX ARE INCLUDED. (RCB)